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1 import inspect |
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2 import os |
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3 |
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4 from django.conf import settings |
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5 from django.core.exceptions import ImproperlyConfigured |
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6 from django.utils.importlib import import_module |
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7 |
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8 DEFAULT_DB_ALIAS = 'default' |
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9 |
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10 # Define some exceptions that mirror the PEP249 interface. |
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11 # We will rethrow any backend-specific errors using these |
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12 # common wrappers |
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13 class DatabaseError(Exception): |
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14 pass |
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15 |
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16 class IntegrityError(DatabaseError): |
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17 pass |
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18 |
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19 |
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20 def load_backend(backend_name): |
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21 try: |
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22 module = import_module('.base', 'django.db.backends.%s' % backend_name) |
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23 import warnings |
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24 warnings.warn( |
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25 "Short names for DATABASE_ENGINE are deprecated; prepend with 'django.db.backends.'", |
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26 PendingDeprecationWarning |
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27 ) |
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28 return module |
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29 except ImportError, e: |
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30 # Look for a fully qualified database backend name |
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31 try: |
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32 return import_module('.base', backend_name) |
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33 except ImportError, e_user: |
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34 # The database backend wasn't found. Display a helpful error message |
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35 # listing all possible (built-in) database backends. |
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36 backend_dir = os.path.join(os.path.dirname(__file__), 'backends') |
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37 try: |
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38 available_backends = [f for f in os.listdir(backend_dir) |
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39 if os.path.isdir(os.path.join(backend_dir, f)) |
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40 and not f.startswith('.')] |
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41 except EnvironmentError: |
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42 available_backends = [] |
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43 available_backends.sort() |
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44 if backend_name not in available_backends: |
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45 error_msg = ("%r isn't an available database backend. \n" + |
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46 "Try using django.db.backends.XXX, where XXX is one of:\n %s\n" + |
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47 "Error was: %s") % \ |
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48 (backend_name, ", ".join(map(repr, available_backends)), e_user) |
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49 raise ImproperlyConfigured(error_msg) |
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50 else: |
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51 raise # If there's some other error, this must be an error in Django itself. |
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52 |
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53 |
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54 class ConnectionDoesNotExist(Exception): |
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55 pass |
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56 |
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57 |
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58 class ConnectionHandler(object): |
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59 def __init__(self, databases): |
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60 self.databases = databases |
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61 self._connections = {} |
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62 |
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63 def ensure_defaults(self, alias): |
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64 """ |
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65 Puts the defaults into the settings dictionary for a given connection |
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66 where no settings is provided. |
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67 """ |
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68 try: |
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69 conn = self.databases[alias] |
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70 except KeyError: |
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71 raise ConnectionDoesNotExist("The connection %s doesn't exist" % alias) |
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72 |
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73 conn.setdefault('ENGINE', 'django.db.backends.dummy') |
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74 if conn['ENGINE'] == 'django.db.backends.' or not conn['ENGINE']: |
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75 conn['ENGINE'] = 'django.db.backends.dummy' |
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76 conn.setdefault('OPTIONS', {}) |
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77 conn.setdefault('TEST_CHARSET', None) |
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78 conn.setdefault('TEST_COLLATION', None) |
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79 conn.setdefault('TEST_NAME', None) |
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80 conn.setdefault('TEST_MIRROR', None) |
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81 conn.setdefault('TIME_ZONE', settings.TIME_ZONE) |
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82 for setting in ('NAME', 'USER', 'PASSWORD', 'HOST', 'PORT'): |
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83 conn.setdefault(setting, '') |
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84 |
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85 def __getitem__(self, alias): |
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86 if alias in self._connections: |
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87 return self._connections[alias] |
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88 |
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89 self.ensure_defaults(alias) |
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90 db = self.databases[alias] |
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91 backend = load_backend(db['ENGINE']) |
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92 conn = backend.DatabaseWrapper(db, alias) |
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93 self._connections[alias] = conn |
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94 return conn |
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95 |
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96 def __iter__(self): |
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97 return iter(self.databases) |
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98 |
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99 def all(self): |
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100 return [self[alias] for alias in self] |
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101 |
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102 |
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103 class ConnectionRouter(object): |
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104 def __init__(self, routers): |
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105 self.routers = [] |
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106 for r in routers: |
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107 if isinstance(r, basestring): |
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108 try: |
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109 module_name, klass_name = r.rsplit('.', 1) |
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110 module = import_module(module_name) |
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111 except ImportError, e: |
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112 raise ImproperlyConfigured('Error importing database router %s: "%s"' % (klass_name, e)) |
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113 try: |
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114 router = getattr(module, klass_name)() |
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115 except AttributeError: |
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116 raise ImproperlyConfigured('Module "%s" does not define a database router name "%s"' % (module, klass_name)) |
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117 else: |
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118 router = r |
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119 self.routers.append(router) |
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120 |
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121 def _router_func(action): |
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122 def _route_db(self, model, **hints): |
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123 chosen_db = None |
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124 for router in self.routers: |
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125 try: |
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126 chosen_db = getattr(router, action)(model, **hints) |
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127 if chosen_db: |
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128 return chosen_db |
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129 except AttributeError: |
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130 # If the router doesn't have a method, skip to the next one. |
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131 pass |
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132 try: |
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133 return hints['instance']._state.db or DEFAULT_DB_ALIAS |
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134 except KeyError: |
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135 return DEFAULT_DB_ALIAS |
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136 return _route_db |
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137 |
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138 db_for_read = _router_func('db_for_read') |
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139 db_for_write = _router_func('db_for_write') |
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140 |
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141 def allow_relation(self, obj1, obj2, **hints): |
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142 for router in self.routers: |
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143 try: |
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144 allow = router.allow_relation(obj1, obj2, **hints) |
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145 if allow is not None: |
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146 return allow |
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147 except AttributeError: |
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148 # If the router doesn't have a method, skip to the next one. |
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149 pass |
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150 return obj1._state.db == obj2._state.db |
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151 |
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152 def allow_syncdb(self, db, model): |
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153 for router in self.routers: |
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154 try: |
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155 allow = router.allow_syncdb(db, model) |
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156 if allow is not None: |
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157 return allow |
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158 except AttributeError: |
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159 # If the router doesn't have a method, skip to the next one. |
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160 pass |
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161 return True |